The fire, which broke out about 1:30 a.m., prompted a small number of overnight workers to leave on their own. When firefighters arrived, a hazardous materials team was summoned to seal the ammonia tanks.

As of 4:20 a.m., fire personnel remained on the scene, but the fire had been put out and the tanks disconnected, Curtis said.

Traffic along Lawndale and Archer Avenues remained blocked off for several blocks in both directions due to a heavy presence of fire and police vehicles.